Blue Cat Audio has released a program called Plug n Script, https://www.bluecataudio.com/Products/P ... ugNScript/, that is a toolkit for creating audio plug-ins. The toolkit is capable of building effects or virtual instruments that work with both 32 and 64 bit operating systems and on both the PC and Mac platforms.

The program sits as a DAW insert so you can test whatever you create without leaving your DAW. The creation is sandboxed to prevent accidental DAW crashes.